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The structure and continuous stoichiometry change of 1DTbBr(x)@SWCNTs

Authors/others:Kiselev, N. A. (Russian Academy of Sciences) Kumskov, A. S. (Russian Academy of Sciences) Zhigalina, V. G. (Russian Academy of Sciences) Vasiliev, A. L. (Russian Academy of Sciences) Sloan, J. (University of Warwick) Falaleev, N. S. (Lomonosov Moscow State University (MSU)) Verbitskiy, N. I. (Lomonosov Moscow State University (MSU)) Eliseev, A. A. (Lomonosov Moscow State University (MSU))
Abstract:HRTEM and HAADF STEM of 1DTbBr(x)@SWCNT meta-nanotubes reveal three structural modifications of 1D nanocrystals within single wall carbon nanotube channels attributed to a different stoichiometry of the guest crystal. For SWCNTs with diameters D-m > 1.4 nm a most complete tetragonal unit cell is observed. When crystallization occurs inside SWCNT with D-m <1.4 nm 1D TbBrx crystal deforms a nanotube to elliptical shape in cross section. In this case the 1D crystal unit cell becomes monoclinic, with possible loss of a part of bromine atoms. Two modifications of a monoclinic unit cell appear. One of them is characterized by single or pair vacancies in the structure of the 1D crystal. Another structure is explained by peripheral and central bromine atoms loss. An appearance of such modifications can be stimulated by electron irradiation. The loss of bromine atoms is in agreement with chemical analysis data. Electronic properties of obtained meta-nanotubes are investigated using optical absorption and Raman spectroscopy. It is shown that intercalation of terbium bromide into SWCNTs leads to acceptor doping of SWCNTs. According to local EDX analysis and elemental mapping this doping can arise from significant stoichiometry change in 1D nanocrystal indicating an average Tb:Br atomic ratio of 1:2.8 0.1.
Number of pages:10
Date of publication:4.2016
Journal title:Journal of Microscopy
Digital Object Identifier (DOI):http://dx.doi.org/10.1111/jmi.12348
Publication Type:Article
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